Method of direct ore reduction using a short cap arc heater

ABSTRACT

The oxides of certain metals including iron, chromium, manganese, vanadium and titanium may be finely ground or otherwise pulverized and supplied in a gas flow stream to the heating region of an arc heater. In the heating region an electric arc capable of producing temperatures sufficient to free hydrocarbon radical ions from hydrocarbon gas may be used to assist in separating the metal from the metal oxide ore.

United States Patent [191 Fey et al.

METHOD OF DIRECT ORE REDUCTION USING A SHORT CAP ARC HEATER Inventors:Maurice G. Fey, Turtle Creek;

George A. Kemeny, Murrysville, both of Pa.

Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed: Dec. 15, 1971 Appl. No.: 208,264

Assignee:

us. 01. 75/10 R, 75/11 rm. Cl 0220 7/04 Field of Search 75/10 R, 10 V,10 P,

References Cited V UNITED STATES PATENTS 6/1968 Hirayama et al 23/277 RX [111 3,765,870 Oct. 16, 1973 3,390,979 7/1968 Greene 75/ll PrimaryExaminer-L. Dewayne Rutledge Assistant ExaminerM. .l. AndrewsAttorney-A. T. Stratton et al.

[57] ABSTRACT The oxides of certain metals including iron, chromium,manganese, vanadium and titanium may be finely ground or otherwisepulverized and supplied in a gas flow stream to the heating region of anarc heater. In the heating region an electric arc capable of producingtemperatures sufficient to free hydrocarbon radical ions fromhydrocarbon gas may be used to assist in separating the metal from themetal oxide ore.

5 Claims, 1 Drawing Figure METHOD OF DIRECT ORE REDUCTION USING A SHORTCAP ARC HEATER BACKGROUND OF THE INVENTION This invention relates toelectric arc heaters in general and in particular to electric archeaters adapted for reducing metal oxides.

The reduction process for some metal oxides includes the use of a blastfurnace in which iron ore is reduced by the reactive effect of hotcar-bon monoxide produced from coke. Electric furnaces or are heatershave been developed which use electric arcs to assist in the reductionof metal oxides, usually in combination with a gas such as oxygen,carbon monoxide, hydrogen or certain hydrocarbon gases. An example ofsuch a furnace is shown in U.S. Pat. No. 3,232,746 entitled Method ForReduction of Metal Oxide by B. Karlovitz. In this case, a hydrocarbongas is partially burned and supplied to a reduction furnace betweenelectrodes, whereupon a diffused electric charge is established in theflame to increase its energy sufficiently to heat and reduce the ore tothe metallic state. The carbon monoxide and hydrogen may react withvarious metal oxides such as iron ore to convert the iron ore into ironand gaseous byproducts. In this case, the iron is precipitated off toform a molten pool which may be later tapped for conversion of the ironto steel.

In another example, as disclosed in U.S. Pat. No. 3,390,979 entitledDirect Steel Making Process" by A.E. Greene, particles of certain metaloxides are supplied to one end of an elongated vertical chamber in whichan arc is longitudinally struck. A reduction gas is passed into thechamber in the opposite direction from the other end and allowed to flowupwardly past the arc and the metal particles. As the reaction processtakes place the byproduct gases are tapped out of the top of thevertical chamber at a different exhaust port and the metal precipitatesout through the bottom of the vertical chamber.

Both of these inventions have disadvantages. One of these is thetemperature to which the reducing gas is raised as in thefirst-mentioned patent and'another disadvantage is the dependence upongravity in a vertical chamber and the generation of a continuous ratherlarge arc in the latter patent. It would be advantageous to provide anarc heater apparatus adapted to expose a hydrocarbon gas to an electricarc rather than a diffused electric discharge pattern so that the gasmaybe raised to an extremely high temperature sufficient to generate thehydrocarbon radical ion rather than merely the carbon monoxide andhydrogen which can be produced at lower temperatures so that variousmetal oxides other than iron may also be reduced. In addition, thehydrocarbon ion reacts so speedily when compared with carbon monoxideand hydrogen inreducing metal oxides that the metallic oxide feedstockmay be injected into the arc chamber at extremely high speeds, bereacted upon speedily, and the resulting metal may be supplied throughan exhaust chamber in the form of a fluid or liquid stream of generallypure metallic particles to another process apparatus which may use thefluid metal as a component element.

SUMMARY OF THE INVENTION In accordance with the present invention,various arc heater apparatus which may be adapted to be supplied withfluid streams of porous material from at least two regions into thevicinity of a high energy, high temperature electric arc may be appliedto reduce metal oxides which flow in one of the streams by-generallyconcurrently reducing a hydrocarbon based gas which may be flowing inanother stream to produce the hydrocarbon radical ion which, for thepurpose of illustration, may be described as Cl-I (in which X may be anynumber from one to three). One of the characteristics of the disclosedmethod is that the metal oxide may be pulverized or otherwise finelyground and fed into a high velocity axially oriented stream of gas whichflows axially into the arc chamber of an arc heating apparatus. The vhydrocarbon gas which may be methane, acetylene or propane may passsubstantially perpendicularly through an electric are which has beenstruck in a gap in the arc heater chamber and into the stream of theoncoming metal oxide bearing gas. The electric arc is provided to reducethe hydrocarbon gas and to'generally simultaneously produce ashort-lived hydrocarbon radical ion which immediately reacts with themetal oxide to reduce the metal oxide to a metal which is thenforcefully blown out of the exhaust port of the are heating' chamber.This high reaction rate allows for the reduction of more metal oxide perunit time as well as moving corrosive byproducts from the reaction areaquickly. Examples of arc heating apparatus which may be quickly adaptedto perform the function previously described are shown and described inU.S. Pat. Nos. 3,445,191 by A.M. Bruning et al entitled Arc HeaterApparatus for Chemical Processing, in U.S. Pat. No. 3,522,015 by DA.Maniero et al entitled Direct Conversion Chemical Processing Arc Heaterand in U.S. Pat. No. 3,705,975 by GE. Wolfe et al entitled Self-Stabilizing Arc I-Ieater Apparatus all of which are assigned to theassignee of the present application. Other arc heating apparatus similarto those mentioned may also be adapted to perform the functionspreviously described.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of theinvention, reference may be had to the preferred embodiment exemplary ofthe invention shown in the accompanying drawing inwhich:

The sole FIGURE shows a sectional view in elevation of an arc heaterapparatus adapted to perform the methods of the disclosed invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the FIGURE, across-sectional view of an arc heater as previously described in U.S.Pat. No. 3,705,975 is shown. The are heater apparatus 10 includes a leftelectrode chamber 12 and a right electrode chamber 14 having electrodes16 and 18 respectively which are generally cylindrical, and coaxiallydisposed on a common axis 52 and spaced by a narrow gap 20. In thepreferred embodiment of the invention, an electric arc 22 may be struckin the narrow gap 20 either by a direct current or alternating currentbackup source of power, whereupon the arc may be blown into the arcchamber by the force of a gas or fluid 24 being injected or providedinto the arc chamber through the narrow gap 20. It is not necessary inall embodiments of the invention for the arc to be blown far out intothe arc chamber as is shown in the FIGURE. It is merely necessary forthe arc to heat the hydrocarbon gas and for the feedstock or metallicoxide bearing gas to come in contact with the arc to some reasonabledegree.

Electrode chambers 12 and 14 are supported by generally rigid supportingmeans 26 and 28 respectively which may by fastened together so that agas introduction means 23 which may include manifolds for channeling thegas 24 into the arc chamber region may be placed adjacent gap 20. Inaddition, part of magnetic flux producing means which may be either ofthe permanent or the electromagnetic variety and which may be usedsingularly or in cooperation are shown at 30 and 32. These means may beprovided to produce a magnetic field within the region of the arcchamber to cause the roots of arc 22 to precess or move under theinfluence of the magnetic field around the inner surface of theelectrodes 16 and 18. In addition, cooling means may be provided to theelectrodes 16 and 18 as indicated by chambers or paths 38, 39, 40 and 41in the FIGURE. Water or a similar cooling medium may be supplied toports 34 on 36 with one port acting as an input port and the otheracting as an exhaust port for the cooling fluid.

Adjacent to one end of the opened arc chamber formed by the electrodes16 and .18 may be placed a feedstock injection means 43 sufficientlyfastened to the open end of the electrode 18 by a fastening means suchas 42 shown in the FIGURE. The feedstock injection means may include ahollow, central tubular orifice, having an axis 52, through which ametal oxide bearing gas 48 may be supplied into the arc chamber region.The metal oxide bearing gas may contain finely ground or minuteparticles of the metal oxide ores of such metals as iron, vanadium,manganese, chromium or titanium, for example. It should be understoodthat the reduction process is not limited to oxides ofthese particularmetals, but may be used for any metal oxide which may be finelypulverized and carried upon an injection stream such as indicated at 48and be reduced by the enhanced reduction power of the hydrocarbonradical ion. Adjacent the other end of the arc heating apparatus is anexhaust port 51 through which a stream of metal bearing gas'50 may beconducted. In some instances, the force of the injection atinjectionmeans 43 may be sufficient to blow the reduced metal out of theexhaust 'port 51 in liquid or droplet form or in a fine mist. v

In the operation of the apparatus, the hydrocarbon gas 24 is provided tothe gap 20 at a relatively cool supply temperature, whereupon it isexposed to the high temperature and energy of, the electric are 22 whichmay raise the temperature of thegas to extreme values to form thehydrocarbon radical ionCH which may be CH for example. These hydrocarbonradicals have very short lives and may be produced quite rapidly ingreat volume from hydrocarbon gas by the presence of the electric are22. The metal oxide may be directly exposed to the arc and thehydrocarbon ion whereupon almost instantaneous reduction of the metaloxide may take place, allowing the resultant metal to. continue to flowas shown by gas flow arrow 50 quickly out ofthe exhaust end 51 of thearc heating apparatus 10. This fluid metal may be used in a furtherprocess without the necessity for storing, collecting or precipitatingit. Hydrogen and carbon product type gases may be introducedsimultaneously into the region of the gap rather than pure hydrocarbongas to achieve the same desired result, namely the formation of thehydrocarbon ion which is so beneficial in quickly capturing the oxygenof the metal oxides and providing relatively pure metal as an outputproduct from the chemical process. In some instances, it may bedesirable to use a metal oxide bearing gas which is also a hydrocarbonso that the electric arc may break down the hydrocarbon as it speedspast the electric arc, forming the hydrocarbon ion which quickly reducesthe metal oxide in the immediate vicinity of the arc.

It is to be understood that although a horizontal high speed processingapparatus is shown, it may also be vertically oriented. The relativespeed of the feedstock metal oxide bearing gas may be varied accordingto the particular needs of the chemical process. At times, it may berelatively slow and at other times it may approach sonic velocity. It isalso to be understood that the hydrocarbon gas such as shown by arrows24 may be any suitable gas or combinations of gases adapted to generatea hydrocarbon radical ion. It is to be understood that carbon atoms orions and carbon monoxide molecules may also be formed incidentally as abyproduct of the heating of the hydrocarbon gas by the arc, but thatthese ions or atoms, although they are beneficial in capturing some ofthe oxygen from the metallic oxides, are not envisioned to be the mainreactant in the reduction process. It is also to be understood that theexit porthole 51 of the arc heater 10 may correspond to an Entranceporthole for another process mechanism or apparatus. In some instances,the hydrocarbon gas may be provided through the feedstock channel 46 andthe metal oxide may be provided through the gap 20, the results beingvirtually the same in both cases. It is also to be understood that thegas 24 which is provided to the gap 20 may blow the electric arc outinto the arc chamber for a more efficient exposure to the metal oxidebearing gases and may assist in swirling or rotating the are ifdesirable to prevent damage to the surfaces of the electrodes 16 and 18.

The apparatus involving the teachings of this invention has manyadvantages, one of which is the capability of reducing metal oxideswhich could not otherwise be reduced by conventional chemical reactionprocesses. As an example, carbon and carbon monoxide ions and atoms arenot effective for reducing the oxides of vanadium or chromium whereasthe hydrocarbon radical ion is effective for reducing the oxide of thesemetals and producing the metal in its pure state. Another advantage isthe high speed with which the operation may be accomplished due to therelatively high free energy available in the hydrocarbon ion to reduce.metal oxides quickly and efficiently even though these ions have a veryshort life. Another advantage of the present invention is thatthe shortgap are heater generally creates a stable are. It is also an advantageof the present application that the reaction takes place quickly andvitually entirely within the region of the electric are so that noreactive processes are continued as the stream of liquid metal is blownout of the exhaust port and into another reactive process, for example.This means that the output product of the present invention is morelikely to be a substantially pure metal rather than partially reducedmetal oxide.

common axis which form an arc chamber therein having two ends, said arebeing maintained at a temperature for at least a portion of its lifesufficient to produce free hydrocarbon radical ions from hydrocarbongas;

providing generally forcefully, relatively cool hydrofeeding, generallyforcefully, from one end of said arc chamber metal oxide in a pathgenerally parallel to said axis through one of said hollow electrodesand to said region in said arc chamber containing said portion of saidare and said free radical ions to thereby chemically react generallysimultaneously with said free radical ions to produce a relativelyaxially oriented fluid stream of metal; and

feeding said axially oriented fluid stream of metal through said otherhollow electrode to an exhaust part at the other end of said arechamber.

2. The method as claimed in claim 1, including the additional step of:

moving the roots of said are generally circumferentially along the innersurfaces of said electrodes by interaction of the electric current ofsaid are near said surface with magnetic field lines generated by amagnetic fieldproducing means adjacent said electrodes. I a

3. The method as claimed in claim 2, wherein said metal oxide comprisesiron oxide and said hydrocarbon gas comprises methane.

4. The method as claimed in claim 2, wherein said metal oxide comprisesiron oxide and said hydrocarbon gas comprises propane.

5. The method as claimed in claim 2, wherein said metal oxide comprisesiron oxide and said hydrocarbon gas comprises acetylene.

UNITED STATES PATENT- OFFICE CERTIFICATE OF CORRECTION Patent No.376587O Dated October 1973 Inventofls) Maurice F n George Kemeny It iscertified that error appears in the above-identified patent and .thatsaid Letters Patent are hereby correctefi as shown belbw:

Column 1, lines 1 and 2, cancel [5 4] METHOD OF DIRECT ORE REDUCTIONUSING A SHORT CAP ARC HEATER" and substitute [5 4] METHOD OF DIRECT OREREDUCTION USING A SHORT GAP ARC HEATER Signed and sealed this 21st dayof May 197i;-

(SEAL) Attest:

.EZDJIARD I'IJLIJTGHER,JR. G. MI-U'KSHALL DAL-IN Attesting OfficerCommissioner'- of Patents FORM PO-1050 (1M9) I UlcOMNl-OC 60315-960 'anu. sovnnlmu PIIITII onlcl nu 0-in-8

2. The method as claimed in clAim 1, including the additional step of:moving the roots of said arc generally circumferentially along the innersurfaces of said electrodes by interaction of the electric current ofsaid arc near said surface with magnetic field lines generated by amagnetic field producing means adjacent said electrodes.
 3. The methodas claimed in claim 2, wherein said metal oxide comprises iron oxide andsaid hydrocarbon gas comprises methane.
 4. The method as claimed inclaim 2, wherein said metal oxide comprises iron oxide and saidhydrocarbon gas comprises propane.
 5. The method as claimed in claim 2,wherein said metal oxide comprises iron oxide and said hydrocarbon gascomprises acetylene.